1. Field of the Invention
The present invention relates to an electronic in which a semiconductor element is utilized. More particularly, the present invention relates to a circuit on which a driver IC for driving a display panel used in a portable device, an electronic databook, a memory, a controller, or the like, is bare-chip mounted, and to an electronic device having this circuit.
2. Description of the Related Art
Conventionally, in the case of mounting a semiconductor chip by using a bump formed on a part of an IC chip, the semiconductor chip is welded by pressure on a substrate by means of an anisotropic conductive film, or a silver paste is printed on the bump to be connected to the substrate with underfill filled therebetween, so that the semiconductor chip is connected on the substrate. As a bump, a stud bump and a plating bump formed by plating the Au bump are used.
In addition, by using a metal diffusion contact, the semiconductor chip could be mounted on the substrate. In this case, according to one known method, by using solder as a bump on the IC, the semiconductor chip is soldered on an electrode of a substrate and the underfill is filled therebetween. In addition, according to another known method, by using Au as a bump on the IC, Sn plating is provided on the electrode of the substrate, Au—Sn diffusion connection is performed between the Au bump of the IC and the Sn plating electrode of the substrate, and then, the underfill is filled therebetween.
For evaluating the connection condition of a semiconductor IC that has been mounted as described above, a method is utilized in which a signal is input to confirm an output waveform, and another method is utilized in which the connection condition is judged by its visual appearance. As mounting defects, a connection defect is detected when the inclination of a bonding head is deviated and a mounting positional deviation may also be considered a defect.
In face down mounting of the semiconductor IC, since a circuit surface of the IC and a terminal surface of the substrate are bonded, the connection part is invisible, so that a defect cannot be confirmed. Therefore, in order to confirm the connection condition, the bonded part is broken down to observe the connection part. However, this method has a problem such that a product is not capable of being inspected one by one.
In addition, according to the method for confirming the output waveform by inputting a signal to the IC, an inspection device becomes expensive and it takes a long time to inspect all products. Furthermore, the connection appearance is unobservable, so that it is not possible to inspect the positional deviation.
Therefore, in order to inspect the conenction and the positional deviation, an inspection bump and an inspection pattern are disposed at each corner of the semiconductor IC and a flexible substrate on which the IC is mounted, respectively, and the connection is confirmed as being in an open- or short-circuit condition. If connection at each corner is established, correlation data may be utilized to determine that there is no problem in the connection. In this case, by making a probe contact a land for inspection, which is derived from each corner, the inspection is performed. As shown in FIG. 11, at each corner of the IC1 which is mounted on a flexible substrate connected to the display panel 6, an inspection land 4 is provided. However, it is the often the case that it is difficult to arrange an inspection land 4 at each corner in the product design. In the case that the inspection land is installed at each corner, as seen by the display unit shown in FIG. 11, the outer shape of the product becomes large due to the installation of the inspection lands. In order to reduce the size of the outer shape of the product, from two opposing corners of the IC or from two positions on a longer side of the IC, the inspection land is derived to perform the inspection. However, a mounting defect in the corner at an uninspected portion is not capable of being inspected, so that a defective flow can be observed. In the case of automatic mounting, the mounting of the IC involves a problem of loose amount of defective products during the positional deviation and the parallelism deviation.